1. Field of the Invention
The present invention is directed to a method for transmitting voice data in data packets upon utilization of additional supplymentary service, wherein a terminal unit working in packet-based fashion transmits and receives voice data in data packets.
2. Description of the Prior Art
A data packet usually contains a plurality of data words with a predetermined plurality of bit places; for example, what are referred to as octettes having eight bit places. In general, octettes that belong to the data header can be distinguished in a data packet. For example, the destination of the data packet is indicated in the data of the data header. On the other hand, for example, data is also contained in the data header that determine the type of data packet. In addition to the data header, there are usually octettes that contain the payload information; for example, the voice data. Data words also are transmitted that form an end section of the data packet and contain, for example, a checksum for error recognition and error correction.
Standards for methods of transmitting voice data in data packets are prescribed, among other things, in the following ITU-T Recommendations (International Telecommunication Union-Telecommunication):
H.323, xe2x80x9cPacket based multimedia communications systemsxe2x80x9d, 02/98;
H.450.1, xe2x80x9cGeneric functional protocol for the support of supplementary services in H.323xe2x80x9d, Jan. 27, 1998;
H.450.2, xe2x80x9cCall transfer supplementary service for H.323xe2x80x9d, Jan. 27, 1998; and
H.450.3, xe2x80x9cCall diversion supplementary service for H.323xe2x80x9d, Jan. 27, 1998.
The basic concept for transmitting multimedia data in data packets is standardized in the Standard H.323. This basic concept, in particular, also applies to the transmission of voice data.
The Standard H.450.1 contains general definitions for the methods and signaling protocols for realizing additional supplymentary service in the connection between what are referred to as H.323 devices; i.e., devices that work according to the Standard H.323. The Standard H.405.1 thus forms the basis for the Standards H.450.2 and H.450.3 that are directed to individual supplymentary service.
The Standard H.450.2 contains definitions for the supplymentary service of xe2x80x9ccall transfer.xe2x80x9d Given the supplementary service xe2x80x9ccall transfer ,xe2x80x9d a calling A-subscriber first sets up a connection to a called B-subscriber. When the connection has been set up, the A-subscriber then calls a third C-subscriber and subsequently hangs up. After the A-subscriber has hung up, there is a connection between the B-subscriber and the C-subscriber.
The Standard H.450.3 contains definitions for the supplementary service xe2x80x9ccall division.xe2x80x9d This supplementary service makes it possible for the call to be rerouted to some other terminal equipment before the setup of a connection.
According to the Standards H.450.2 and H.450.3, supplementary service usually are made available in the terminal equipment themselves. The terminal equipment is therefore constructed in a complex way and has an extensive program system. A central instance for the supplementary service usually is not required.
Traditional voice terminal equipment transmits the voice data in data channels. In the simplest case, a voice channel is formed by a line that is used only for a single connection. Analog or digital voice data is exchanged via the line without interruption by information for connection control. Usually, however, the voice data belonging to different connections is transmitted on a line in the time-division multiplex method. A time section for the transmission of the voice data is defined for each connection within time frames that follow one another in time.
Given traditional ISDN terminal equipment (Integrated Services Digital Network) and, in particular, given system telephones at private branch exchanges (PBS), there are a multitude of other, additional supplementary service; for example:
call waiting;
charge display;
three-party conference;
hold for inquiry;
negotiating;
blocking outgoing calls;
connection without dialing, what is referred to as baby call; and
call back when busy.
It is to be anticipated that standards will be prescribed little by little by the ITU for these additional supplementary service-these containing definitions for using the supplementary service given a transmission of voice data in data packets. However, several years will pass before such standards are defined. After the publication of binding standards, these must be converted into programs for the drive of H.323 terminal equipment so that another development time will have to be provided. Only after this can the user of H.323 terminal equipment employ all additional supplementary service that are already standard for the voice transmission in a voice channel given ISDN terminal equipment and system telephones. There is also a similar situation given other methods for the transmission of voice data in data packets.
An object of the present invention, therefore, is to specify simple methods for transmitting voice data in data packets with additional performance features wherein additional supplementary service can be used without great standardization, development or, respectively, programming outlay for terminal units. Further, electronic units and programs should be specified that serve for the implementation of the methods.
Accordingly, the present invention considers the fact that additional supplementary service have been present for a long time in switching equipment for circuit switching of voice connections in a circuit-switched telecommunication network; for example, in a network wherein voice data is transmitted in voice channels, such as in telecommunication systems of Siemens AG. Since the supplementary service are centrally performed in the switching equipment, the terminal equipment to be connected to the switching equipment is constructed comparatively simply. For example, the desire to use a supplementary service is signaled to the switching equipment from a telephone. In response thereto, the supplementary service of the switching equipment is activated. The switching equipment likewise sends signals to the telephone given employment of the supplementary service with which, for example, signal tones are generated or numerical sequences are sent to the telephone.
The present invention is also based on the perception that it is possible, with respect to the additional supplementary service, to forego the realization of the supplementary service in the terminal equipment for the transmission of voice data in data packets as in the case of terminal equipment for the transmission of voice data in the voice channel to be directly connected to the switching equipment; i.e., without an interface unit for the conversion of transmission signals. Terminal equipment that works in packet-based fashion thus also can be simply constructed because only measures for signaling between terminal equipment and exchange equipment have to be implemented in the terminal equipment. By contrast, no measures that relate to the actual supplementary service need be implemented in the terminal equipment.
In the inventive method, the terminal unit working in packet-based fashion is connected to the switching equipment with the assistance of an interface unit. The interface unit converts transmission signals coming from the switching equipment into transmission signals for the terminal unit, and converts transmission signals coming from the terminal unit into transmission signals for the switching equipment. During use of the additional supplementary service in the switching equipment for controlling the terminal equipment working in packet-based fashion, method steps are implemented in the inventive method that are to be implemented in the use of the additional supplementary service in the switching equipment for controlling terminal equipment connectable to the switching equipment without an interface unit for protocol conversion for the transmission of voice data in a voice channel. The method steps implemented in the switching equipment are, thus, the same at the terminal equipment for the transmission of voice data in data packets and at terminal equipment for the transmission of voice data in a voice channel. The interface unit ultimately connects the terminal device for the transmission of voice data in data packets to the exchange as though it were terminal equipment for the transmission of voice data in a voice channel.
In the inventive method, the switching equipment controls the terminal equipment given utilization of the supplementary service.
Control denotes that method steps in the terminal equipment are triggered by method steps executed in the switching equipment. The control is effected such that a method step in the terminal equipment corresponds to each method step in the switching center. Control commands from the switching equipment, thus, must be forwarded to the terminal equipment.
In the inventive method, the known supplementary service can be used in a simple way because only a comparatively small program for signaling to the exchange and for the interpretation of the signaling coming from the exchange need be stored in the terminal equipment working in packet-oriented fashion. A program for effecting the supplementary service themselves is not required in the terminal equipment working in packet-oriented fashion. As a result of the inventive method, the known and already implemented supplementary service can be used for the transmission of voice data in a voice channel given a connection between terminal equipment working in packet-based fashion and terminal equipment directly connectable to the switching equipment. The supplementary service also can be utilized when two pieces of terminal equipment working in packet-based fashion respectively have a connection to switching equipment.
In one development of the inventive method, the additional performance feature is selected at the side of the terminal unit. For example, the user using the terminal unit working in packet-based fashion decides to initiate what is referred to as a three-party conference. The terminal unit signals the interface unit the selection according to a signaling protocol employing data packets for data transmission networks working in packet-based fashion. The interface unit forwards the received signaling data to the switching equipment according to a signaling protocol defined for the switching equipment. The signal protocol is, thus, modified in the interface unit. For example, the signaling protocols can be modified by an unambiguous imaging of the signaling data of the one signaling, protocol onto the signaling data of the other signaling protocol. The interface unit only sends signaling data to the switching equipment of the same type that terminal equipment connectable to the switching equipment without the interface unit for protocol modification generates for the transmission of voice data in a voice channel.
In another development of the inventive method, the additional supplementary service is selected at the side of the switching equipment. This occurs either by traditional terminal equipment connected to the switching equipment (for example, with a digital telephone for long distance traffic), or by terminal equipment for the transmission of voice data in data packets that is connected via a different interface unit. The switching equipment executes the supplementary service and, upon execution of the additional supplementary service, sends signals or, respectively, signaling data to the interface unit according to a signaling protocol defined for the switching equipment. These signals agree with signals that would be transmitted upon execution of the additional supplementary service for a traditional terminal device connectable without the interface unit.
The signaling protocol defined for the switching equipment is, for example, a matter of an internal company signaling protocol of the manufacturer of the switching equipment. For example, such a signaling protocol is employed for signaling between the telecommunication system HICOM of Siemens AG and terminal equipment of the OPTISET type. In the development of the inventive method, the interface unit is driven by the switching equipment like terminal equipment that transmits the voice data in a voice channel.
In the development of the inventive method, the interface unit forwards the received signals according to a signaling protocol employing data packets for data transmission networks that work packet-oriented. The interface unit, thus, also modifies the signaling protocol in the other direction; i.e., from the switching equipment to the terminal unit.
The signaling protocol for the switching equipment is usually what is referred to as a stimulus protocol wherein only simple instructions are sent to the terminal equipment, these effecting a signaling in the terminal equipment that is visible to the user; for example, the output of signal tones or the display of numerals on a numerical display. The terminal equipment, in turn, merely signals simple signals to the switching equipment given a stimulus protocol; for example, picking up the receiver or the actuation of a specific key. The packet-based signaling protocol for the terminal equipment, by contrast, is usually what is referred to as a functional protocol wherein signaling is carried out dependant on the internal switch status of the terminal equipment. The adaptation of stimulus protocol and functional protocol can be implemented in that, for example, the switch status of the terminal equipment or, respectively, the switch status of the switching equipment as well is simulated in the interface unit. This is possible because the sequence of switch statuses in the switching equipment as well as the sequence of switch statuses in the terminal equipment directly connectable to the switching equipment are known.
Given exchanges wherein a functional protocol is employed for control, the conversion into the signaling protocol employed between the interface unit and the terminal equipment can be implemented even more simply than given a stimulus protocol. Given a functional protocol, there is a specific command in the switching center for each function. Accordingly, the terminal equipment must generate such a command and transmit it to the interface unit. A separate conversion method then can be implemented in the interface unit for each command.
However, methods are also employed wherein a protocol adaptation is implemented with the assistance of what is referred to as tunneling. In tunneling, terminal equipment is employed that process commands coming from the switching center. These commands are embedded in the signaling unit into commands that are transmitted between the signaling unit and the terminal equipment in data packets. In the other direction, the terminal equipment generates commands for the switching center that, however, are likewise embedded into data packets. The data packets are unpacked in the signaling unit, and the commands are forwarded unmodified to the control of the switching center. The content of the command is thereby not modified. When the commands employed in the switching center change, then only programs that would have to be changed anyway in order to use the new commands need be modified in the switching center and in the terminal equipment. The programs in the interface unit, by contrast, need not be modified.
In another development of the method of the present invention, a signaling protocol working according to the ITU-T Standard H.323 is employed as signaling protocol for the terminal equipment. The standard allows an expansion by new signaling commands that are directed to the utilization of additional supplementary service or tunneling. When the signaling protocol defined for the switching equipment likewise works on the basis of data packets, as is in the case given modern switching equipment, then the structure of the signaling unit is simplified.
In a development of the inventive method, the voice data is transmitted from the terminal unit to the interface unit according to a transmission protocol for data packets. The interface unit unpacks the voice data and forwards the received voice data to the switching equipment according to a protocol defined for voice transmission in a voice channel. The interface thus implements a conversion of the transmission protocol for voice data transmitted from the terminal unit to the switching equipment.
In another development, a conversion of the transmission protocols also is implemented in the other direction. The switching equipment thereby sends voice signals to the interface unit according to a method for voice transmission in a voice channel. The interface unit forwards the received voice signals to the terminal unit according to a transmission protocol for packet-based transmission.
In one development, a protocol that corresponds to the ITU-T Standard H.323 is employed as transmission protocol for the voice data. The method for the transmission in the voice channel in one development is a time-division multiplex method; for example, a PCM method (pulse code multiplex).
In another development of the inventive method, the terminal unit is connected to the interface unit via a data transmission network wherein data is transmitted on the basis of data packets. At least one piece of terminal equipment with which voice data can be transmitted in the data transmission network is connected to the data transmission network. For example, the Internet or an Intranet wherein the Internet protocol IP/TCP (Internet Protocol/Transfer Control Protocol) is employed is used as data transmission network. As a result of these measures, terminal equipment can be connected to switching equipment in a simple way.
In another development, an access device connected to the data transmission network controls the access of the terminal equipment to the data transmission network. A conversion of the telephone number of the circuit-switched telecommunication network into an address of a piece of terminal equipment of the data transmission network or in the opposite direction is implemented in the access device. This conversion can be incorporated in a simple way in the access device because basic functions for such a conversion already must be present therein. The access device is also referred to as xe2x80x9cgatekeeperxe2x80x9d in English.
The present invention is also directed to a line/trunk group for the packet-oriented voice transmission with which the above-explained method or, respectively, the developments thereof can be implemented. The technical effects cited above, thus, also apply to the line/trunk group.
A further aspect of the present invention is directed to a switching equipment with the inventive assembly. By employing the assembly, the performance features present in the switching equipment are also accessible to a packet-based voice transmission.
A next aspect of the invention is directed to an apparatus that contains the inventive line/trunk group. The aforementioned technical effects thus likewise apply to the inventive switching equipment and to the inventive device.
The aforementioned object also is achieved by a method that is closely related to the first inventive method because similar steps are implemented; these, however, are related to the terminal equipment. In the second inventive method, a voice, transmission unit of the terminal equipment transmits voice data according to a packet-based transmission protocol. In addition to the basic functions for the transmission of voice signals, at least one additional supplementary service can be employed for the packet-oriented voice transmission in an operating interface. A signaling unit transmits signaling data according to a packet-based signaling protocol between a data transmission network for the transmission of data packets and the terminal equipment. Upon use of the additional supplementary service the voice transmission unit, the signaling unit is driven such that signaling commands are sent into the data transmission network that indicate that the additional supplementary service is to be used. Alternatively or additionally, the signals the signaling unit receives from the data transmission network are checked and, given reception of signals that indicate the utilization of the supplementary service, the voice transmission unit and/or the operating interface is driven such as required by the supplementary service. The aforementioned technical effects apply to the second inventive method because these effects also arise when only the terminal unit is considered that is suitable for the implementation of the first inventive method. The second inventive method is also utilized in the developments of the first inventive method.
The present invention is also directed to a unit and to a program that are employed for the packet-oriented voice transmission according to the second inventive method or, respectively, the developments thereof. The technical effects cited for the second inventive method are also valid for the apparatus and the program.